The invention relates to brake systems, and more particularly, to a rim brake, as for a bicycle.
Bicycles typically employ one of three different kinds of brakes. The relative popularity of these brakes is based mainly on the type of bicycle to which they are affixed. Urban bikes usually use internal gear hubs with a coaster brake in the rear wheel and a rim brake at the front wheel. Mountain bikes typically have disc brakes, and road and triathlon style bikes typically have rim brakes because rim brakes are lightweight and aerodynamic.
There are two different popular kinds of rim brakes on the market. A first is a two post brake and a second is a single pivot brake. The two post brake usually has a gear connection between the left and the second arms, which connects both arms and reduces the apparatus to one degree of freedom. A disadvantage of a two post brake is the different pad path of each brake arm. This kind of brake is also heavier than a single pivot brake because it has more components and every component needs to be of high strength in order to deal with high brake loads. The only disadvantage of the single pivot brake is the asymmetric pad movement caused by different friction experienced by each arm and the asymmetric side load from the cable. These brakes have two degrees of freedom and a spring for each arm to push each arm back to the outer positions. If a higher side load than the preload of the spring is exerted upon one arm, the brake pad attached to that arm would touch the rim all of the time.
The invention provides a bicycle with a rim brake that is not heavy or complex and has suitable performance characteristics.